I would agree with Zen, if you are totally new to this, start with the very basics of TCP/IP, Network Topologies, network communication and playing with OSs .... I would again insist on having a lap computer for learning purposes .... find a cheap one .. and start playing with everything .... install firewall and start testing and observing your computer behavior .... Don't take this as a pure game ... be serious with results ...

And one of the most important things, is participating in specialized public forums like AO ... you will learn enormously about many things .... it just needs willpower and presistance ....

READ READ READ ..... PRACTICE PRACTICE PRACTICE

Cheers